This is a note to let you know that I've just added the patch titled
powerpc/thp: Use ACCESS_ONCE when loading pmdp
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-thp-use-access_once-when-loading-pmdp.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7e467245bf5226db34c4b12d3cbacfa2f7a15a8b Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Wed, 13 Aug 2014 12:32:02 +0530
Subject: powerpc/thp: Use ACCESS_ONCE when loading pmdp
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
commit 7e467245bf5226db34c4b12d3cbacfa2f7a15a8b upstream.
We would get wrong results in compiler recomputed old_pmd. Avoid
that by using ACCESS_ONCE
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/hugepage-hash64.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/powerpc/mm/hugepage-hash64.c
+++ b/arch/powerpc/mm/hugepage-hash64.c
@@ -84,7 +84,9 @@ int __hash_page_thp(unsigned long ea, un
* atomically mark the linux large page PMD busy and dirty
*/
do {
- old_pmd = pmd_val(*pmdp);
+ pmd_t pmd = ACCESS_ONCE(*pmdp);
+
+ old_pmd = pmd_val(pmd);
/* If PMD busy, retry the access */
if (unlikely(old_pmd & _PAGE_BUSY))
return 0;
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
queue-3.14/powerpc-thp-use-access_once-when-loading-pmdp.patch
queue-3.14/powerpc-thp-add-write-barrier-after-updating-the-valid-bit.patch
queue-3.14/powerpc-mm-use-read-barrier-when-creating-real_pte.patch
queue-3.14/powerpc-thp-handle-combo-pages-in-invalidate.patch
queue-3.14/powerpc-thp-invalidate-old-64k-based-hash-page-mapping-before-insert-of-4k-pte.patch
queue-3.14/powerpc-thp-invalidate-with-vpn-in-loop.patch
queue-3.14/powerpc-thp-don-t-recompute-vsid-and-ssize-in-loop-on-invalidate.patch
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